Unable to upload images via Flash Upload

Up till about 2 months ago, I was using Flash Upload to upload all my images. I'm using the Tarski theme and initially thought it was due to my flash application. Whenever I attempt to use it, I get "I/O Error. #2038" message.

I'm using a shared computer with my boyfriend, and he is using a different theme and is able to use the flash upload so I'm guessing the problem lies with the Tarski theme. Anyone who could help, thanks in advance.

I have contacted Support and they've told me to delete cookies, cache etc which are things that I've already known and done, without much success. I still can't use the Flash uploader. Anyone who has the same problem and know of any solutions, please help. It is very frustrating.